**3. Corn silage**

38 Aflatoxins – Detection, Measurement and Control

and seeds used in feed for dairy cattle are naturally in contact with yeasts and filamentous fungi, the contamination of raw materials occurs frequently in the field, because of the infection of plant symbiotic fungi as phytopathogens. This contamination can also occur during harvesting, transport and storage of these products and post harvest mishandling can lead to rapid spoilage. In well-preserved forages fungal growth depends on moisture conditions of the plant during harvest. Stored feed, moisture, temperature and oxygen availability are key conditions that determine risk degree of fungal contamination. The critical water activity for safe storage is 0.7 to 0.8 (Magan & Aldred 2007; Scott, 1957). When this level is exceeded, large degrading ability fungi as *Eurotium sp.*, and species of *Aspergillus* and *Penicillium* can grow. Increase in respiratory activity, due to the development of these fungi, leads to an increase in the temperature of feed that can lead to the contamination by other

Silage is one of the main constituents in the diets of dairy cattle and its deterioration and aflatoxin contamination can lead to considerable production losses and a major impact on

In many systems of milk production mainly in the northern hemisphere, the dairy cows are housed in stockyard due to extreme weather conditions, either high or low temperatures. These intensive production systems use a minimal proportion of grass per cow. In other systems, where climates are more benign and temperate, the production system is typically

In general, worldwide, the diversity of soils, climates and production scales do not allowa single production system; it is clear that there has been a gradual shift from purely pastoral models to semi-intensive systems (López 2008). In the first instance, the producers began to incorporate ration, preferably, corn grain or commercial feed and for this, they took the shackles of milking, where feeders are installed. Simultaneously, the corn silage began to spread, both as a reserve fodder as well as balanced diet. At this point, producers required

This intensification is necessarily accompanied by a significant increase of the scale, this fact

The development in milk production in recent years has followed an intensification which has resulted in a change in the use of feed, evolving from simple grazing feeding systems

Although the current systems of feeding in major milk producing areas in Argentina have particular differences in the degree of intensification, they can be considered supplement grazing systems (or semi-intensive). Through this enhancement, production level was able to grow extensively. The levels of milk production increased from 12 L to 20-30 L. However, animal numbers by hectare did not increase. That supplementation can not only avoid the seasonality of production due to the availability of pastures in different seasons, but also allow to balance the dietary components optimizing milk production per cow (West, 2003). However, many authors argue not to forget grass, which remains the staple feed "of

causes many people to use new technologies to keep the cows in confinement.

based on mixed feed formulation combining grains and forages.

ruminant herbivores" as well as the cheapest cost of production. The composition of feed rations for dairy cows consists of: Pastures (including small grain winter and summer)

fungi especially thermophilic fungi and, therefore, to further deterioration.

**2. Breeding and feeding systems on dairy farms** 

human health.

extensive grazing.

new ways of providing meals.

Conserved forage (silage, hay)

Concentrate

Corn (*Zea mays* L.) is the most widely grown crop in the Americas, extensively used for animal feeding and human consumption due to its nutritional value. A large percentage of the world corn production is destined to animal feeding. Silage is a widespread practice to preserve forages during extended time periods. The production of corn silage entails incorporation of the whole plant and its storage is based on the principle of preservation under anaerobic conditions with growth of lactic acid bacteria which promote a natural fermentation that lowers the pH to a level at which clostridia and most fungal growth are inhibited. In dairy cows, silage is a preferred food by the vast majority of producers.

As corn silage consists of grinding and storing the whole corn plant, it includes not just grain but a high percentage of stalks and stover and represents a new important bulky feed source for dairy and beef cattle. Nutritionally, corn silage, for example, has a balance between the energy density of the grain and fibber and digestibility of the green plant that makes it suitable for feeding ruminants in the phases of maximum nutritional needs (Molina et al., 2004).
